000 AXPZ20 KNHC 162158 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Aug 16 2023 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Tropical Storm Hilary is centered near 13.7N 103.7W at 16/2100 UTC, moving west-northwest at 13 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous strong convection covers a widespread area in the Mexico offshore waters and the high seas from 06N to 17N between 98W and 111W. Peak seas are around 17 ft with the 12 ft seas extending within 270 nm in the NE quadrant, 240 nm in the SE quadrant, 120 nm in the NW quadrant, and 105 nm in the SW quadrant. Hilary will continue to move west-northwest with a gradual turn to the northwest by Friday followed by a turn to the north-northwest on Saturday. Steady to rapid strengthening is forecast for the next few days. Hilary is expected to become a hurricane on Thursday. Large swells generated by Hilary will affect portions of the coast of southwestern Mexico and the Baja California peninsula over the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. Seas are expected to become high or very high by Thu and phenomenal by Fri. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Fernanda NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Tropical Storm Fernanda is centered near 16.8N 127.8W at 16/2100 UTC, moving west at 12 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Scattered moderate convection is noted in the western semicircle from 16N to 18N between 128W and 131W. Peak seas are around 22 ft with the 12 ft seas extending 120 nm in the NE quadrant, 105 nm in the NW quadrant, and 90 nm in the southern semicircle. Fernanda will continue moving westward for the next few days. Continued weakening is forecast during the next couple of days, and Fernanda is likely to become a post-tropical cyclone by tonight and dissipate by the weekend. Seas will drop below 12 ft by Fri morning and will continue to quickly subside through the weekend. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Fernanda NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave is along 89W from 08N northward to the coast of El Salvador, moving W at 10 to 15 kt. Scattered moderate convection is noted from 05N to 13N between 88W and 91W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica near 08N82W to 10N94W, then from 10N109W to 11N124W. The ITCZ extends from 08N130W to beyond 07N140W. Scattered moderate to isolated strong convection is noted from 04N to 08N between 79W and 87W. Scattered moderate convection is noted from 07N to 14N between 112W and 126W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features for information on Tropical Storm Hilary. Outside of TS Hilary, a surface ridge dominates the offshore forecast waters of Baja California. This is causing moderate NW to N winds off Baja California Norte with light to gentle winds elsewhere in the Baja California offshore waters, confirmed by scatterometer data this afternoon. Seas are 4 to 6 ft in mixed swell. In the Gulf of California, light to gentle variable winds are noted with seas of 1 to 2 ft, except seas of 3 to 4 ft near the entrance to the Gulf. Light to gentle winds are elsewhere off the southern Mexico offshore waters with 4-6 ft seas in mostly SW swell. For the forecast, Tropical Storm Hilary will move to 14.5N 105.4W Thu morning, strengthen to a hurricane near 15.6N 107.6W Thu afternoon, 16.8N 109.6W Fri morning, 18.2N 111.3W Fri afternoon, 20.0N 112.8W Sat morning, and 22.3N 113.7W Sat afternoon. Hilary will change little in intensity as it moves near 27.8N 115.2W by Sun afternoon. Looking ahead, an area of low pressure could form south of the Gulf of Tehuantepec over the weekend. Some gradual development of this system is possible thereafter while it moves generally west-northwestward. This system has a low chance of tropical cyclone development over the next 48 hours and 7 days. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to locally strong winds are seen in the Papagayo region, and downwind to near 89W according to the latest scatterometer data. Seas range 5 to 8 ft in this area. Moderate southerly winds are noted off the Ecuador coast with light to gentle winds elsewhere across the Central America and South American offshore waters. Seas are generally 4 to 6 ft due to long-period SW swell, except 1 to 3 ft in the Gulf of Panama, and 3 to 5 ft just offshore Colombia. For the forecast, fresh to locally strong winds are expected in the Papagayo region trough Sun night. Winds will increase to moderate between Ecuador and the the Galapagos Islands waters tonight and will persist through the weekend. Expect moderate seas within S to SW swell in this area. ...REMAINDER OF THE AREA... Please refer to the Special Features section above for details on Tropical Storm Fernanda. A ridge dominates roughly the waters N of 20N and W of 115W. The pressure gradient between the ridge and tropical cyclone Fernanda supports an area of moderate winds, which scatterometer depicts mainly from 15N to 24N between 121W and 140W. Light to gentle winds are noted elsewhere under the influence of the ridge, N of 23N and W of 124W. Gentle to locally moderate S to SW winds are noted S of the ITCZ/monsoon trough. Seas range 4-7 ft across the forecast waters within NW swell. For the forecast, based on latest NHC forecast advisory, Fernanda will become post-tropical and move to 16.6N 130.0W Thu morning, weaken to a remnant low near 16.6N 132.6W Thu afternoon, 16.7N 135.3W Fri morning, 16.7N 138.0W Fri afternoon, 16.7N 140.6W Sat morning, and dissipate Sat afternoon. $$ AReinhart